<template>
  <div class="todo-container">
    <div class="todo-wrap">
      <Header @add-todo="addTodo" />
      <List :todos="todos" :deleteTodo="deleteTodo" :checkTodo="checkTodo" />
      <!-- <h2 v-if="!todos.length">请添加一个todo项</h2> -->
      <Footer
        v-if="todos.length"
        :todos="todos"
        :checkAllTodo="checkAllTodo"
        :clearAllDone="clearAllDone"
      />
    </div>
  </div>
</template>

<script>
import Header from "./components/Header";
import List from "./components/List";
import Footer from "./components/Footer";

export default {
  name: "App",
  components: { Header, List, Footer },
  data() {
    return {
      todos: JSON.parse(localStorage.getItem('todos')) || [],
    };
  },
  methods: {
    // 用于添加一个todo对象
    addTodo(obj) {
      // 看一下当前的todos中是否有与要添加的名字重复的todo项
      const result = this.todos.find((item) => item.title === obj.title);

      //#region
      // 完整写法（过几天我要盯上你了）
      /* const result = this.todos.find( (item) => {
            return item.title === obj.title
          }) */
      //#endregion

      // 如果没有，就添加
      if (result) {
        alert("不能重复添加");
      } else {
        this.todos.unshift(obj);
      }
    },
    // 用于删除一个todo对象
    deleteTodo(id) {
      this.todos = this.todos.filter((item) => {
        return item.id !== id;
      });
    },
    // 用于勾选or取消勾选
    checkTodo(id) {
      this.todos.forEach((item) => {
        if (item.id === id) {
          item.done = !item.done;
        }
      });
    },
    // 用于全选or全不选
    checkAllTodo(flag) {
      this.todos.forEach((item) => {
        item.done = flag;
      });
    },
    // 用于清除所有已完成
    clearAllDone() {
      this.todos = this.todos.filter((item) => {
        return !item.done;
      });
    },
  },
  watch:{
    todos:{
      deep:true,
      handler(value){
        localStorage.setItem('todos',JSON.stringify(value))
      }
    }
  }
};
</script>

<style>
/*base*/
body {
  background: #fff;
}
.btn {
  display: inline-block;
  padding: 4px 12px;
  margin-bottom: 0;
  font-size: 14px;
  line-height: 20px;
  text-align: center;
  vertical-align: middle;
  cursor: pointer;
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.2),
    0 1px 2px rgba(0, 0, 0, 0.05);
  border-radius: 4px;
}
.btn-danger {
  color: #fff;
  background-color: #da4f49;
  border: 1px solid #bd362f;
}
.btn-danger:hover {
  color: #fff;
  background-color: #bd362f;
}
.btn:focus {
  outline: none;
}
.todo-container {
  width: 600px;
  margin: 0 auto;
}
.todo-container .todo-wrap {
  padding: 10px;
  border: 1px solid #ddd;
  border-radius: 5px;
}
</style>